Building the SOHA

[heady 0]

I am gathering the bits and pieces needed to built this beauty. I need some advice as to the best (meaning nice to deal with and reasonable cost) place to pick up the tube and tube socket. And can the gurus please give their recommendations on what tubes to buy.

 

Note that I am an impoverished newbie (cos of my hobby) so please be moderate in your recommendations.

 

And do you guys think a toroidal transformer is necessary? I used a normal transformer for my PPA and I can hear low buzz in mid-volume in low impedence phones. Interestingly, there is no buzz on low or high volume. With my DT880, no buzz at all.

 

[Kippei 0]

toroidal transformer i got no idea how to get it in Singapore. For my PPA mine is a DC adaptor which i pass a tread through it...

[heady 0]

Can get toroidal transformer from Farnell, for example, I am thinking of getting this one for the SOHA:

 

Farnell order code = 9531670 (Sorry, can't link to it, the website will expire the session)

 

It has secondaries 2x15V, 15VA and cost $28.47. And it is potted with a plastic frame, so hopefully easier to fix onto the casing.

Edited August 13, 2006 by heady

[jasonhanjk 0]

Should be ok. Just make sure the transformer is far away from your amp.

[heady 0]

Thanks Jason. Anyone with info re: tubes??

[siriuz 0]

There was some discussion about DIY-ed SOHAs some time ago, I think it would be a good read for people who are interested in building their own SOHAs.

 

Here's a post from that thread, with info regarding 12AU7 (and various substitutes) tubes:

 

http://www.sgheadphones.net/index.php?showtopic=4263&st=160#

[heady 0]

Thanks siriuz, it shows how old I am. I plain forgot this thread. From the thread you've given, looks like I got serious tube rolling plus good money to blow... ouch, I feel for my wallet.

 

 

 

 

 

[heady 0]

Got a question for the electronics experts. I followed the published BOM and bought the TO92 form regulators instead of the TO220. My question is, are the pinouts of the TO92 regulators standard?

 

Ie for the positive regulators, regardless of the manufacturer, the pinouts are the same. And same for the negative regulators. I know the positive and negative regulators have different pinouts.

 

The reason I am asking is that someone told me that because Digi's board is for the TO220 form, they are not right for the TO92 form, so I need to check the pinouts.

 

What I found, is that the pinouts for the TO92 and TO220 are the same for the positive regulators and similarly, the negative regulators. So am I missing something?

 

Thanks.

[jasonhanjk 0]

TO220 have higher thermal dissipation and higher current than TO92. Plug it in and if less than 50 degrees C, you're good.

[mb3k 0]

What Alps pot are you guys using? The 50K version or 100K?

[heady 0]

I will be using the 50K version. Got it from Tangent.

[Qsilver 0]

I usually skim on the vol pot, using RK097. hehe

Invest on better parts.

[heady 0]

qsilver, true I have not been able to discern any SQ difference between the RK09 and the RK27 series. But the latter definitely feels nicer when turning the knob.

Edited August 23, 2006 by heady

[Qsilver 0]

I do agreed, if xtra $$ is available upon after getting other parts. IMO

[mb3k 0]

Just got another set of PCB's off of somebody else. Which project guide are you guys following? The one off of headwize? That one doesn't seem to have all the latest and greatest info.